As an automatic sheet feeding apparatus, in which a stack of papers is separated and separated papers are fed out one by one, there is known an apparatus shown in FIG. 8.
In this apparatus, a plurality of stacked papers P are placed on a supporting plate, and a feed-in roller 1 and a friction roller 2 are rotated in a direction indicated by an arrow to feed the papers P toward a dividing belt 3. When the papers P arrive at a contact point of the dividing belt 3 and the friction roller 2, the lowermost paper is delivered out by the frictional force of the friction roller 2 because the delivering force of the friction roller 2 overcomes the retreating force of the dividing belt 3, but the second paper and upper papers are prevented from advancing by the dividing belt.
Namely, the friction roller and belt are arranged so that a relation of .mu..sub.R &gt;.mu..sub.B &gt;.mu..sub.p is established among the friction coefficient .mu..sub.R of the friction roller 2 to the paper, the friction coefficient .mu..sub.B of the dividing belt 3 to the paper and the friction coefficient .mu..sub.p of the papers to each other. By this arrangement, the lowermost paper alone is separated from the upper papers and fed out.
In this paper feeding apparatus, in order to enhance the dividing capacity in feeding a plurality of papers, it is necessary to increase the contact pressure between the dividing belt 3 and the friction roller 2. In this case, if thin papers being easy to be folded are fed, the top ends of papers are readily butted against the dividing belt and bent to cause a phenomenon of so-called paper jamming. If the contact pressure of the dividing belt 3 to the friction roller 2, is decreased, occurrence of paper jamming is prevented, but if a plurality of thick and hard papers are fed at one time, the dividing belt 3 rises from the surface of the friction roller 2 and the dividing capacity is reduced, with the result that two or more papers are sometimes fed at one time.